Metallocene catalysts containing an idenyl moiety substituted at the 4,-5,-6- or 7-position by a siloxy or germyloxy group

ABSTRACT

A metallocene catalyst in which the metal is coordinated by a η 5  cyclopentadienyl ligand which forms part of an indenyl or indenyloid moiety, characterised in that said moiety is directly or indirectly substituted at the 4-, 5-, 6- or 7-position by a pendant siloxy or germyloxy group.

[0001] This invention relates to catalysts for olefin polymerisation, inparticular to catalysts which comprise a metal bonded to a pentahapto(η⁵) cyclopentadienyl moiety, fused to at least one 6-membered ring.

[0002] In olefin polymerizations, it has long been known to use as acatalyst system the combination of a metallocene procatalyst and analumoxane co-catalyst or catalyst activator.

[0003] By “metallocene” is meant here a metal complex which comprises atleast one ligand complexed to a metal and having a hapticity of 2 orgreater, for example 2 to 5, especially 5. Metallocenes which compriseone or more pentahapto (η⁵) ligands, for example the cyclopentadienylligand, have assumed greatest importance and the subsequent discussionwill focus mainly on but is not limited to this subtype ofmultihapto-containing metal-ligand complexes.

[0004] The metallocene may for example be a so-called “open sandwich” or“half sandwich” compound in which the metal is complexed by a singlemultihapto η⁵ ligand; a “sandwich” compound in which the metal iscomplexed by 2 or more such ligands; a “handcuff compound” in which themetal is complexed by a bridged bis-multihapto ligand, for example abis-η⁵-ligand; or a “scorpionate compound” in which the metal iscomplexed by a multihapto (e.g. η⁵) ligand bridged to a η¹ (for examplea σ-bonded) ligand.

[0005] Metallocenes have been much used in the copolymerization ofolefins, especially ethylene, propylene, other α-olefins and higherolefins, in the presence of a co-catalyst/catalyst activator such as analumoxane.

[0006] Alumoxanes are compounds with alternating aluminium and oxygenatoms, generally compounds of formula I or II

R₂Al—(O—AlR)_(p)—O—AlR₂  (I)

[0007]

[0008] where each R, which may be the same or different, is a C₁₋₁₀alkyl group, and p is an integer having a value between 0 and 40). Thesecompounds may be prepared by reaction of an aluminium alkyl with water.The production and use of alumoxanes is described in the patentliterature, especially the patent applications of Texas Alkyls,Albemarle, Ethyl, Phillips, Akzo Nobel, Exxon, Idemitsu Kosan, Witco,BASF and Mitsui.

[0009] Traditionally, the most widely used alumoxane is methylalumoxane(MAO), an alumoxane compound in which the R groups are methyl groups.MAO however is poorly characterised, appears to comprise a range ofcage-like structures more complex than the simple linear or cyclicstructures of formulae I and II, and is relatively expensive.Accordingly, efforts have been made to use alumoxanes other than MAO.Thus, for example WO98/32775 (Borealis) proposes the use of metalloceneprocatalysts with alumoxanes in which R is a C₂₋₁₀ alkyl group, e.g.hexaisobutylalumoxane (HIBAO).

[0010] The contents of WO98/32775 and all other publications referred tohereafter are hereby incorporated by reference.

[0011] Much effort has been expended into the development of improvedmetallocene-containing catalyst systems on account of the economicimportance of olefin polymers. Of particular relevance are theinvestigations into indenyl-containing metallocenes in which the5-membered cyclopentadienyl ring bonds in a η⁵ fashion to the metal inthe complex. For example WO 97/28170 (Borealis) discloses investigationsinto the substitution of the 5-membered ring of the indenyl moiety withalkoxy, siloxy and other groups. U.S. Pat. Nos. 5,672,668, 5,504,232 and5,304,613 (all to Winter et al.) disclose, inter alia, handcuffcompounds or other metallocenes comprised of indenyl-based complexes,particularly those in which the 6-membered ring in the indenyl moiety isfunctionalised with one or more hydrocarbyl or halohydrocarbylsubstituents.

[0012] U.S. Pat. No. 5,483,002 (to Seelert et al.) discloses similartypes of bis indenyl-based metallocenes. Exemplary of such 5,6 fusedsystems is the indenyl system.

[0013] Chiral C₂-symmetric bis(indenyl) ansa-metallocenes are precursorsto highly active catalysts for stereoselective polymerisation ofalpha-olefins. The performance characteristics of these systems aredifferent, the variations being induced by size and position of thesubstituents. For example, dimethylsilylene bridged2,2′-dimethyl-4,4′-diaryl substituted bis(indenyl) zirconocenesdeveloped by Brintzinger and co-workers (Organometallics 1994, 13, 964)and Spaleck et al. (Organometallics 1994, 13, 954), catalyse theproduction of isotactic polypropylenes with catalyst activities andpolymer properties comparable to those obtained with heterogeneousZiegler-Natta catalysts.

[0014] Research into electronically altered indenyl and bis(indenyl)metallocenes, however, has remained relatively sparse. So too arereports of electronically modified indenyloid and bis(indenyloid)ligands. As used herein, the term indenyloid is intended to embrace thegeneral class of anions formed by the deprotonation of any 5,6-fusedsystem whereby to form a cyclopentadienyl η⁵ ligand fused to a6-membered ring. Indenyl itself may be considered as the parentindenyloid but will be referred to as indenyl here. The fluorenyl ligandis an example of an indenyloid ligand.

[0015] Previously, it has been reported that halogen or alkoxysubstitution in the six-membered rings of indenes reduces the activityof the catalyst system and the molecular weight of the produced polymer(Consiglio et al., Organometallics 1990, 9, 3098; Collins et al.,Organometallics 1992, 11, 2115). Bis(indenyl) zirconocenes with 2-aminofunctionalised ligands have been reported by several groups (Luttikheddeet al., Organometallics 1996, 15, 3092; Plenio and Burth, J. Organomet.Chem. 1996, 519, 269; Brintzinger et al., J. Organomet. Chem. 1996, 520,63). The bridged complexes show somewhat lower catalytic activitiescompared with their unsubstituted bis(indenyl) zirconocene analogues.

[0016] WO 97/28170 (supra) does in some way address this neglected area.However, this publication addresses the issue of electronicallymodifying, by way of substitution, the 5-membered ring of indenyl andindenyloid compounds whereby to produce metallocene compounds in whichan oxygen atom is directly bonded to the 2-position of a η⁵ indenylmoiety.

[0017] However, there have been no reports of metallocenes in which the6-membered ring of an indenyl or indenyloid ring has been electronicallymodified by substitution by a pendant heteroatom attached group at the4- or 7-position (i.e. a position adjacent to an atom participating inboth the 5- and 6-membered rings).

[0018] Surprisingly, however, it has been found that a number of suchcompounds, viz metallocenes coordinated by a η⁵ indenyl or indenyloidmoiety in which a 6-membered ring fused directly or indirectly to the5-membered ring is substituted by a siloxy or germyloxy group, exhibitadvantageous properties. These complexes, when used as procatalysts inα-olefin polymerisation, allow the production of α-olefin homo orcopolymers with notably higher molecular weight than achievable withanalogous compounds in which the 6-membered ring is not substituted by asiloxy or germyloxy group. Moreover the activity of these complexes inpolymerisations is high, as measured by the quantity of polymer producedper unit time against the quantity of metallocene used; and incopolymerisations, the complexes of the invention result in highercomonomer incorporation than do analogous compounds in which the6-membered ring is not substituted by a siloxy or germyloxy group.

[0019] Viewed from one aspect, therefore the present invention providesa metallocene catalyst in which the metal is coordinated by a η⁵cyclopentadienyl ligand which forms part of an indenyl or indenyloidmoiety, characterised in that said moiety is directly or indirectlysubstituted at the 4- 5-, 6- or 7-position, preferably the 4- or7-position, by a pendant siloxy or germyloxy group.

[0020] As used herein the term metallocene catalyst is intended toembrace the actual catalytic species. This may be the metallocenecompound itself or a metallocene procatalyst by which term is meant acompound which may be brought into a catalytically active state (e.g.for catalysis of α-olefin polymerization) by reaction with a co-catalystor catalyst activator, e.g. an aluminium alkyl or other aluminiumcompound or a boron compound.

[0021] The metal will generally be a transition metal or lanthanide,especially a Group 3 (i.e. including scandium) to Group 7 (i.e.including manganese) transition metal, particularly a Group 4 to 6metal, in particular Zr, Ti or Hf. For the avoidance of doubt,lanthanide metals herein include lanthanum itself.

[0022] Viewed from a further aspect, the invention provides an olefinpolymerisation catalyst system comprising or produced by the reactionof:

[0023] (i) a metallocene catalyst in which the metal is coordinated by aη⁵ cyclopentadienyl ligand which forms part of an indenyl or indenyloidmoiety, characterized in that said moiety is directly or indirectlysubstituted at the 4- 5-, 6- or 7-position by a pendant siloxy orgermyloxy group; and

[0024] (ii) a cocatalyst/catalyst activator, e.g. an aluminium alkylcompound, in particular an alumoxane, especially an aluminum alkylcompound comprising alkyl groups containing from 1 to 6 carbon atoms.

[0025] Alternatively, said aluminum alkyl compound may be one whichcontains at least two carbon atoms.

[0026] Viewed from a still further aspect, the invention provides aprocess for olefin polymerisation comprising polymerising an olefin inthe presence of a metallocene catalyst in which the metal is coordinatedby a η⁵ cyclopentadienyl ligand which forms part of an indenyl orindenyloid moiety, characterised in that said moiety is directly orindirectly substituted at the 4- 5-, 6- or 7-position by a pendantsiloxy or germyloxy group.

[0027] Viewed from a yet another aspect, the invention provides aprocess for the preparation of a metallocene catalyst which comprisesmetallating a η⁵ cyclopentadienyl ligand which forms part of an indenylor indenyloid moiety with a transition metal or lanthanide,characterised in that said moiety is directly or indirectly substitutedat the 4- 5-, 6- or 7-position by a pendant siloxy or germyloxy group.

[0028] Alternatively, it will be understood that the metallocenecatalyst may be produced by the exchange of a metal ion in an existingmetallocene for another metal ion through transmetallation.

[0029] Viewed from a different aspect, the invention provides an olefinpolymer produced in a polymerisation process catalysed by an olefinpolymerisation catalyst system comprising or produced by the reaction of

[0030] (i) a metallocene catalyst in which the metal is coordinated by aη⁵ cyclopentadienyl ligand which forms part of an indenyl or indenyloidmoiety, characterised in that said moiety is directly or indirectlysubstituted at the 4- 5-, 6- or 7-position by a pendant siloxy orgermyloxy group; and

[0031] (ii) a cocatalyst/catalyst initiator, e.g. an aluminium alkylcompound, in particular an alumoxane, especially an aluminum alkylcompound comprising alkyl groups containing from 1 to 6 carbon atoms.

[0032] Alternatively, said aluminum alkyl compound may be one whichcontains at least two carbon atoms.

[0033] Viewed from an alternative aspect, the invention provides the usein olefin polymerisation of a metallocene catalyst in which the metal iscoordinated by a η⁵ cyclopentadienyl ligand which forms part of anindenyl or indenyloid moiety, characterised in that said moiety isdirectly or indirectly substituted at the 4- 5-, 6- or 7-position by apendant siloxy or germyloxy group.

[0034] By directly or indirectly is meant that the pendant siloxy orgermyloxy group is either directly bonded to one of the carbon atoms atposition 4, 5, 6 or 7 (throughout this specification the numbering ofcarbon atoms is derived from the IUPAC numbering scheme for the indenylring) or is attached to one of these atoms, for example, by way of oneor more intervening atoms, which may form a fused ring.

[0035] For the avoidance of doubt, however, the invention does notrelate to metallocene catalysts containing only η⁵ cyclopentadienylligands which form part of an indenyl or indenyloid moiety which containonly one or more directly bonded siloxy or germyloxy substituents at the1-, 2- or 3- positions and no other siloxy or germyloxy substituentselsewhere.

[0036] Thus the catalyst of the invention may for example be a compoundof formula (III):

(Lig)_(p) M(X)_(m)(A)_(n)  (III)

[0037] in which:

[0038] M is a transition metal ion or a lanthanide metal ion;

[0039] p is 1 or 2;

[0040] m is greater than or equal to 0;

[0041] n is greater than or equal to 0;

[0042] n+m is equal to the valency of the metal not satisfied by ligandor ligands Lig;

[0043] X is a ligand which co-ordinates to M (for example a η⁵hydrocarbyl, η¹ hydrocarbyl, halo, hydrocarbyl amino or hydrocarbylamido ligand);

[0044] A is a σ-ligand as defined hereinafter; and

[0045] each ligand Lig which may be the same or different is a η⁵cyclopentadienyl ligand which forms part of an indenyl or indenyloidmoiety, characterised in that said moiety is directly or indirectlysubstituted at the 4- 5-, 6- or 7-position by a pendant siloxy orgermyloxy group, for example (Lig)_(p) may be one or two of ligands Inas defined hereafter.

[0046] M in the metallocene catalysts of the invention is preferably agroup 4 to 6 transition metal, e.g. a metal selected from Ti, Zr, Hf, V,Nb, Ta, Cr, Mo and W. However, the metal is preferably Cr, Ti, Zr or Hf,particularly Cr if M is liganded by a single multihapto group or Ti, Zror Hf if M is η-liganded by one or more multihapto groups.

[0047] Useful indenyl or indenyloid ligands according to the inventionmay be represented by symbol “In” wherein In consists of a negativelycharged indenyl or indenyloid moiety of the following formula (IV):

[0048] wherein one or more of the ring carbon atoms may be replaced by aring heteroatom;

[0049] each Q is either a silicon or a germanium atom;

[0050] either or both of the bonds shown as—may be present or absent;

[0051] each R¹ which may be the same or different is a hydrogen or aC₁₋₂₀ hydrocarbyl especially an alkenyl or alkyl group, especially aC₁₋₈ group, or a η¹ ligand (for example a σ ligand such as anitrogen-containing group such as amine, at least one R¹ being otherthan hydrogen;

[0052] each R² may be hydrogen or a group bonded to the 5-membered ringthrough an atom of groups 14, 15 ot 16 of the periodic table (IUPAC)carbon, oxygen, silicon, germanium, nitrogen or sulfur, e.g. C₁₋₂₀hydrocarbyl, hydrocarbyl siloxy, hydrocarbyloxy, hydrocarbylgermyloxy,hydrocarbyl silyl or hydrocarbylgermyl group particularly an oxygen-,silicon-, germanium- or sulfur-attached hydrocarbyl group;

[0053] each R³ may be hydrogen or a group bonded to the 6-membered ringthrough an atom of groups 14, 15 ot 16 of the periodic table (IUPAC)carbon, oxygen, silicon, germanium, nitrogen or sulfur, e.g. C₁₋₂₀hydrocarbyl, hydrocarbyl siloxy, hydrocarbyloxy, hydrocarbylgermyloxy,hydrocarbyl silyl or hydrocarbylgermyl group particularly an oxygen-,silicon-, germanium- or sulfur-attached hydrocarbyl group; or

[0054] two or more R² and/or two or more R³ groups attached to adjacentring atoms on the same ring together form a 5- to 8-membered fused ring;and optionally

[0055] one R² or R³ is -L-Z wherein L is a 1 to 4 atom chain and Z is asecond moiety, which may the same as or different to said first moiety,preferably of formula (IV) and joined to L through one R² or R³, ifpresent in which L is one and the same chain common to both moieties,

[0056] a is an integer between 1 and 3,

[0057] b is an integer between 1 and 3, the sum of a and b being no morethan 4,

[0058] c is an integer between 1 and 3,

[0059] with the proviso that no more than one -L-Z group is present ineach ligand In.

[0060] Preferably L-Z where present is attached to the 5-membered ring,especially at the 1- or 3-positions or less preferably to the 6-memberedring at the 4- or 7 positions.

[0061] The ligands in themselves are novel and form a further aspect ofthe invention. Viewed from this aspect, therefore, there is provided aligand of formula (IV)

[0062] (wherein one or more of the ring carbon atoms may be replaced bya ring heteroatom;

[0063] each Q is either a silicon or a germanium atom;

[0064] either or both of the bonds shown as—may be present or absent;

[0065] each R¹ which may be the same or different is a hydrogen or aC₁₋₂₀ hydrocarbyl especially an alkenyl or alkyl group, especially aC₁₋₈ group, or a η¹ ligand (for example a σ ligand such as anitrogen-containing group such as amine, at least one R¹ being otherthan hydrogen;

[0066] each R² may be hydrogen or a group bonded to the 5-membered ringthrough an atom of groups 14, 15 ot 16 of the periodic table (IUPAC)carbon, oxygen, silicon, germanium, nitrogen or sulfur, e.g. C₁₋₂₀hydrocarbyl, hydrocarbyl siloxy, hydrocarbyloxy, hydrocarbylgermyloxy,hydrocarbyl silyl or hydrocarbylgermyl group particularly an oxygen-,silicon-, germanium- or sulfur-attached hydrocarbyl group;

[0067] each R³ may be hydrogen or a group bonded to the 6-membered ringthrough an atom of groups 14, 15 ot 16 of the periodic table (IUPAC)carbon, oxygen, silicon, germanium, nitrogen or sulfur, e.g. C₁₋₂₀hydrocarbyl, hydrocarbyl siloxy, hydrocarbyloxy, hydrocarbylgermyloxy,hydrocarbyl silyl or hydrocarbylgermyl group particularly an oxygen-,silicon-, germanium- or sulfur-attached hydrocarbyl group; or

[0068] two or more R² and/or two or more R³ groups attached to adjacentring atoms on the same ring together form a 5- to 8-membered fused ring;and optionally

[0069] one R² or R³ is -L-Z wherein L is a 1 to 4 atom chain and Z is asecond moiety, which may the same as or different to said first moiety,preferably of formula (IV) and joined to L through one R² or R³, ifpresent in which L is one and the same chain common to both moieties,

[0070] a is an integer between 1 and 3,

[0071] b is an integer between 1 and 3, the sum of a and b being no morethan 4,

[0072] c is an integer between 1 and 3,

[0073] with the proviso that no more than one -L-Z group is present ineach ligand In) and salts and complexes thereof.

[0074] For the avoidance of doubt, ligands In include homocyclic orheterocyclic indenyl/indenyloid moieties which may be optionally fusedto other rings.

[0075] By fused or non-fused is meant that the indenyl or indenyloidligand may have two carbon or heteroatoms also forming part of anadditional ring which may itself by fused or an optionally substitutedcarbocyclic or heterocyclic ring etc. For example the fluorenyl ring isembraced by this invention.

[0076] By homo- or heterocyclic is meant that any ring of the indenylligand or indenyloid ligand may have only carbon ring atoms (i.e. homoor isocyclic) or may have ring atoms other than carbon (heterocyclic).Such ring heteroatoms may for example be, independently from each other,N, S, Se, O, P, B or Si.

[0077] The variables a, b and c are all preferably 1 or 2, espcially 1.

[0078] Preferred ligands In are those in which at least one group offormula —OQ(R¹)₃ is a siloxy or germyloxy group directly attached to the4-position or the 7-position or indirectly attached to the 4-, 5-, 6- or7-position. Also preferred are ligands In in which one or more of saidmoiety or moieties of formula (IV) contain 2 groups of formula (R¹)₃QO—,for example one such group at position 4 and one at position 7 in theindenyl or indenyloid ring.

[0079] In one embodiment, one of the groups R¹ is an amine, e.g.alkylamine, bound to the Si or Ge atom via a carbon atom of said amine,wherein the nitrogen atom acts as a σ-ligand coordinating any metal ionpresent. In such an embodiment it is preferred if L-Z is absent.

[0080] Especially preferably ligands of In are those in which one groupR² is of formula -L-Z. Particularly preferred are those in which -L-Z ispresent at the 1-position and/or in which Z is another moiety of formula(IV), preferably attached to L through an R² group.

[0081] In ligands In, including those preferred types as describedherein, L is preferably of formula (C(R²)₂)_(q) or Si(R²)₂ in which q isone or 2 or more and R² is as hereinbefore defined but may not representa group L-Z) but is preferably hydrogen or a hydrocarbyl group.

[0082] Compounds of formula (III) are preferably of formula(Lig)₂M(A)_(n) wherein M, A and n are as hereinbefore defined; and(Lig)₂ is a ligand In in which one group R² in said first moiety offormula (IV) is -L-Z, where L is preferably of formula (CR²)₂, ((CR²)₂)₂or Si(R²)₂ in which R² is as hereinbefore defined but is preferablyhydrogen or a hydrocarbyl group and Z is a second moiety preferably offormula (IV) which may or may not be the same as the first moiety offormula (IV) with the proviso that L is attached to the 1-position insaid second moiety of formula (IV).

[0083] Preferably, in the moiety or moieties of formula (IV) of ligandsIn there is no other substitution other than the substituents OQ(R¹)₃and R²; i.e. R³═H.

[0084] Particularly preferred ligands In used according to the variousaspects of the present invention are those of formula (V)

[0085] (wherein R¹, R², R³, Q and L-Z are as hereinbefore defined).

[0086] Preferably in ligands In, L is preferably of formula (C(R²)₂)₂ orSi(R²)₂ in which R² is as hereinbefore defined (but is not L-Z) and ispreferably hydrogen or a hydrocarbyl group, for example methyl.

[0087] Examples of suitable (R¹)₃QO groups wherein Q=Si in themetallocene procatalysts of the invention include:

[0088] Thus typical examples of ligands of formula In include mono orbisanions of the following mono and bridged bis indenes:

[0089] Typical examples of the metallocene catalysts of the inventionthus include:

[0090] Examples of particular further η-ligands are well known from thetechnical and patent literature relating to metallocene olefinpolymerization catalysts, e.g. EP-A-35242 (BASF), EP-A-129368 (Exxon),EP-A-206794 (Exxon), WO 97/28170 (Borealis), EP-A-318048, EP-A-643084,EP-A-69951, EP-A-410734, EP-A-128045, EP-B-35242 (BASF), EP-B-129368(Exxon) and EP-B-206794 (Exxon). These include

[0091] cyclopentadienyl,

[0092] indenyl,

[0093] fluorenyl,

[0094] octahydrofluorenyl,

[0095] methylcyclopentadienyl,

[0096] 1,2-dimethylcyclopentadienyl,

[0097] pentamethylcyclopentadienyl,

[0098] pentyl-cyclopentadienyl,

[0099] 2-dimethyl,tertbutylsiloxy-inden-1-yl,

[0100] n-butylcyclopentadienyl,

[0101] 1,3-dimethylcyclopentadienyl,

[0102] 4,7-dimethylindenyl,

[0103] 1,-ethyl-2-methylcyclopentadienyl,

[0104] tetrahydroindenyl, and

[0105] methoxycyclopentadienyl.

[0106] By a σ-ligand moiety is meant a group bonded to the metal at oneor more places via a single atom, eg a hydrogen, halogen, silicon,carbon, oxygen, sulphur or nitrogen atom. Examples of such ligandsinclude:

[0107] halogenides (e.g. chloride and fluoride),

[0108] hydrogen,

[0109] triC₁₋₁₂ hydrocarbyl-silyl or -siloxy(e.g. trimethylsilyl),

[0110] triC₁₋₆ hydrocarbylphosphimido (e.g. triisopropylphosphimido),

[0111] C₁₋₁₂ hydrocarbyl or hydrocarbyloxy (e.g. methyl, ethyl, phenyl,benzyl and methoxy),

[0112] diC₁₋₆ hydrocarbylamido (e.g. dimethylamido and diethylamido),and

[0113] 5 to 7 ring membered heterocyclyl (e.g. pyrrolyl, furanyl andpyrrolidinyl).

[0114] The siloxy or germyloxy indenyl or indenyloid ligands usedaccording to the various aspects of the invention may be prepared by anyconvenient means, for example by reaction of a corresponding indanone,or analogue thereof (for example a 9-fluorenone) in which a 6-memberedring fused to the 5-membered ring is directly or indirectly substitutedwith a hydroxyl group. Such compounds (e.g. 2-hydroxy-9-fluorenone and4- and 5-hydroxy-indanone, which may be purchased from Aldrich) arecommercially available. Alternatively, appropriate hydroxy-substitutedindenes or other polycyclic structures containing the indene skeletonand with one or more appropriate hydroxyl groups, may be used asstarting materials.

[0115] These starting materials may be reacted with a compound offormula (R¹)₃QHal wherein R¹ and Q are as defined above and Hal is anappropriate halide, for example chloride, bromide or iodide (chloridebeing preferred) in a suitable solvent, for example N,N-dimethylformamide (DMF) or dichloromethane.

[0116] Covalent catalysis may be used to assist in such reactions, e.g.effective quantities of triethylamine,1,8-diazobicyclo[5,6,0]undec-7-ene (DBU) or imidazole may be employed.

[0117] Where the starting materials comprise more than one hydroxylgroup such reactions permit the formation of mono- or bis-substitutedsiloxy or germyloxy compounds. Moreover, it is also possible to react anappropriate starting indanone, for example 4-hydroxy-indan-1-one withtwo equivalents of compound of formula (R¹)₃QHal, which may or may notbe the same, to afford the corresponding bis ether of1,4-dihydroxy-ind-1-ene through trapping of the enol tautomer.

[0118] The appropriate siloxy or germyloxy compounds may then beconverted by, for example, a two-step process involving converting theindanone into a hydrazone (e.g. by reaction with tosyl hydrazine), inthe presence of an effective amount of sulfuric acid in methanol;followed by reaction of the so-formed hydrazone with an appropriatebase, e.g. an organolithium compound, such as methyllithium orbutyllithium. The parent reaction here is commonly known as the Shapiroreaction. Particular bases of use in this regard include t-BuLi, n-BuLi,lithium diisopropylamide, t-BuOK, trialkylamines, dialkyl-magnesium,alkylmagnesium chloride, alkyl CuLi and dialkyl zinc which may be usedin conjunction with a suitable solvent. If necessary, a donor such asdimethoxyethane may be added to the reaction medium containing thehydrazone prior to addition of the base.

[0119] Alternatively, the keto group in the indanone may simply bereduced under standard conditions (e.g. sodium borohydride in methanoland/or tetrahydrofuran (THF)) followed by dehydration to form thedesired indene or indene skeleton-containing compound.

[0120] If the formation of a bisindenyl or bisindenyloid ligand (i.e. a“handcuff” ligand as herein before defined) is desirable, twoequivalents (which may or may not be the same) of 1H- or 3H-indene etc.may be reacted with an appropriate base, e.g. an organolithium compound,such as methyllithium or butyllithium. Particular bases and solvents ofuse in this regard are as hereinbefore defined. If necessary, a donorsuch as dimethoxyethane may be added to the reaction medium containingthe appropriate 1H- or 3H-indene etc. prior to addition of the base.

[0121] The anion or anions, as appropriate, may be reacted with amolecule of formula LG₁-L-LG₂ (wherein L is as hereinbefore defined andLG₁ and LG₂ represent any appropriate leaving groups which may or maynot be the same, for example bromide, tosyl, chloride etc., whereby toform the desired bisindenyl ligand. Alternatively, a “handcuff” ligandmay be formed by a two step process in which one equivalent of a firstindenyl anion is reacted with one equivalent of LG₁-L-LG₂ and theresultant indene or equivalent molecule substituted with -L-LG₂ may bereacted with a second molecule anion whereby to form the desired bisindenyl/bis indenyloid ligand.

[0122] Alternatively, wherein R³ is of formula -L-Z, the indenyl toindenyl bridging may be achieved using the methods disclosed inWO96/38458 (Montell).

[0123] Formation of the desired metallocene is effected by reacting thedesired ligand with an appropriate quantity of base, e.g. anorganolithium compound, such as methyllithium or butyllithium (i.e.where formation of a mono η⁵ ligand is desired, one equivalent of baseis used and where a bisindenyl ligand is being used (i.e. a bis η⁵ligand) two equivalents of base may be used. Particular bases andsolvents of use in this regard are as hereinbefore defined. Ifnecessary, a donor such as dimethoxyethane may be added to the reactionmedium containing the appropriate 1H or 3H indene etc. prior to additionof the base.

[0124] The ligand can be metallated conventionally, e.g. by reactionwith a halide of the metal M, preferably in an organic solvent, e.g. ahydrocarbon or a hydrocarbon/ether mixture. Bridged siloxy- or germyloxycyclopentadienyl ligands may be constructed by reacting a siloxy- orgermyloxy monocyclopentadienyl ligand with a bridging agent (e.g.Si(CH₃)₂Cl₂) or with a bridging agent and a further η-ligand (e.g. adifferent cyclopentadienyl ligand or with an indenyl, fluorenyl, etcligand).

[0125] An alternative approach to the complexes is also envisaged wherethe siloxycyclopentadiene is reacted with Zr(NMe₂)₄ or Zr(CH₂Ph)₄followed by Me₃SiCl to yield the complex directly. Also, trimethylsilyl(siloxy) cyclopentadiene reacts with ZrCl₄ to afford the complexdirectly.

[0126] σ-ligands other than chlorine may be introduced by displacementof chlorine from an η-ligand metal chloride by reaction with appropriatenucleophilic reagent (e.g. methyl lithium or methylmagnesium chloride)or using, instead of a metal halide, a reagent such astetrakisdimethylamidotitanium or metal compounds with mixed chloro anddimethylamido ligands.

[0127] Aspects of these synthetic strategies are illustrated in thefollowing schemes which are for illustrative purposes only:

[0128] The cocatalyst of scheme 6 is particularly suitable in thepreparation of isotactic polypropylene and the cocatalyst of scheme 7 isparticularly suitable in high temperature production of polypropylenes.

[0129] The metallocene catalyst and cocatalyst may be introduced intothe polymerization reactor separately or together or, more preferablythey are pre-reacted and their reaction product is introduced into thepolymerization reactor.

[0130] As mentioned above, the olefin polymerisation catalyst system ofthe invention comprises (i) a metallocene catalyst in which the metal iscoordinated by a η⁵ cyclopentadienyl ligand which forms part of anindenyl or indenyloid moiety, characterised in that said moiety issubstituted in the 4- or 7-position by a pendant siloxy or germyloxygroup; and normally (ii) an aluminium alkyl compound (or otherappropriate cocatalyst), or the reaction product thereof.

[0131] While the aluminium alkyl compound may be an aluminium trialkyl(e.g. triethylaluminium (TEA)) or an aluminium dialkyl halide (e.g.diethyl aluminium chloride (DEAC)), it is preferably an alumoxane,either MAO or an alumoxane other than MAO, such as an isobutylalumoxane;e.g. TIBAO (tetraisobutylalumoxane) or HIBAO (hexaisobutylalumoxane).Alternatively, however, the alkylated (e.g. methylated) metallocenecatalysts of the invention may be used with other cocatalysts, e.g.boron compounds such as B(C₆F₅)₃, C₆H₅N(CH₃)₂H:B(C₆F₅)₄,(C₆H₅)₃C:B(C₆F₅)₄ or Ni(CN)₄[B(C₆F₅)₃]₄ ²⁻.

[0132] However, when the metal in the catalyst is a group 3 transitionmetal, i.e. Sc, Y, La or Ac, no co-activator is required since suchcatalyst species are already in an active form, e.g. compounds offormula In₂ScH wherein In is as hereinbefore defined and comprises 2moieties of formula (IV).

[0133] The metallocene catalyst and cocatalyst may be introduced intothe polymerization reactor separately or together or, more preferablythey are pre-reacted and their reaction product is introduced into thepolymerization reactor.

[0134] If desired the catalyst, catalyst/cocatalyst mixture or acatalyst/cocatalyst reaction product may be used in unsupported form,e.g. metallocene and MAO can be precipitated without an actual carriermaterial and used as such. The metallocene catalyst or its reactionproduct with the cocatalyst may also be introduced into thepolymerization reactor in supported form, e.g. impregnated into a porousparticulate support.

[0135] The particulate support material used is preferably an organic orinorganic material, e.g. a polymer (such as for example polyethylene,polypropylene, an ethylene-propylene copolymer, another polyolefin orpolystyrene or a combination thereof). Such polymeric supports may beformed by precipitating a polymer or by a prepolymerization, e.g. ofmonomers used in the polymerization for which the catalyst is intended.However, the support is especially preferably a metal or metalloid oxidesuch as silica, alumina or zirconia or a mixed oxide such assilica-alumina, in particular silica, alumina or silica-alumina.

[0136] Especially preferably the support is a porous material so thatthe metallocene may be loaded into the pores of the support, e.g. usinga process analogous to those described in WO94/14856 (Mobil), WO95/12622(Borealis) and WO96/00243 (Exxon). The particle size is not critical butis preferably in the range 5 to 200 μm, more preferably 20 to 80 μm.

[0137] Before loading, the particulate support material is preferablycalcined, i.e. heat treated, preferably under a non-reactive gas such asnitrogen. This treatment is preferably at a temperature in excess of100° C., more preferably 200° C. or higher, e.g. 200-800° C.,particularly about 300° C. The calcination treatment is preferablyeffected for several hours, e.g. 2 to 30 hours, more preferably about 10hours.

[0138] The support may be treated with an alkylating agent before beingloaded with the metallocene. Treatment with the alkylating agent may beeffected using an alkylating agent in a gas or liquid phase, e.g. in anorganic solvent for the alkylating agent. The alkylating agent may beany agent capable of introducing alkyl groups, preferably C₁₋₆ alkylgroups and most especially preferably methyl groups. Such agents arewell known in the field of synthetic organic chemistry. Preferably thealkylating agent is an organometallic compound, especially anorganoaluminium compound (such as trimethylaluminium (TMA), dimethylaluminium chloride, triethylaluminium) or a compound such as methyllithium, dimethyl magnesium, triethylboron, etc.

[0139] The quantity of alkylating agent used will depend upon the numberof active sites on the surface of the carrier. Thus for example, for asilica support, surface hydroxyls are capable of reacting with thealkylating agent. In general, an excess of alkylating agent ispreferably used with any unreacted alkylating agent subsequently beingwashed away.

[0140] Following treatment of the support material with the alkylatingagent, the support is preferably removed from the treatment fluid andany excess treatment fluid is allowed to drain off.

[0141] The optionally alkylated support material is loaded with thecatalyst. This loading may be effected by using a solution of thecatalyst in an organic solvent therefor, e.g. as described in the patentpublications referred to above. Preferably, the volume of catalystsolution used is from 50 to 500% of the pore volume of the carrier, moreespecially preferably 80 to 120%. The concentration of catalyst compoundin the solution used can vary from dilute to saturated depending on theamount of metallocene active sites that it is desired be loaded into thecarrier pores.

[0142] The active metal (i.e. the metal of the catalyst) is preferablyloaded onto the support material at from 0.1 to 4% preferably 0.5 to3.0%, especially 1.0 to 2.0% by weight metal relative to the dry weightof the support material.

[0143] After loading of the catalyst onto the support material, theloaded support may be recovered for use in olefin polymerization, e.g.by separation of any excess catalyst solution and if desired drying ofthe loaded support, optionally at elevated temperatures, e.g. 25 to 80°C.

[0144] Alternatively, a cocatalyst, e.g. an alumoxane or an ioniccatalyst activator (such as a boron or aluminium compound, especially afluoroborate) may also be mixed with or loaded onto the catalyst supportmaterial. This may be done subsequently or more preferablysimultaneously to loading of the catalyst, for example by including thecocatalyst in the solution of the catalyst, by contacting the catalystloaded support material with a solution of the cocatalyst or catalystactivator, e.g. a solution in an organic solvent, or by firstimpregnating the cocatalyst with a support and then contacting thecocatalyst impregnated support with a solution of the catalyst or neatcatalyst (e.g. as described in WO96/32423). Alternatively however anysuch further material may be added to the catalyst-loaded supportmaterial in the polymerization reactor or shortly before dosing of thecatalyst material into the reactor.

[0145] In this regard, as an alternative to an alumoxane it may bepreferred to use a fluoroborate catalyst activator for the alkylatedcatalysts, especially a B(C₆F₅)₃ or more especially a ^(Θ)B(C₆F₅)₄compound, such as C₆H₅N(CH₃)₂H:B(C₆F₅)₄ or (C₆H₅)₃C:B(C₆F₅)₄. Otherborates of general formula (cation)_(a) (borate)_(b) where a and b arepositive numbers, may also be used.

[0146] As an alternative to the loading of the optionally alkylatedsupport material with a solution of the procatalyst in an organicsolvent, loading of the catalyst may be effected by mixing it with theoptionally alkylated support material in the absence of solvents withsaid carrier at a temperature of at least 50° C. but less than thevaporisation temperature of the metallocene compound. The particularfeatures of this method are disclosed in WO 96/32423 (Borealis). If useof a cocatalyst/catalyst activator in such process is desired, this maybe impregnated into the optionally alkylated support material prior toloading of the catalyst.

[0147] Where such a cocatalyst or catalyst activator is used, it ispreferably used in a mole ratio to the metallocene of from 0.1:1 to10000:1, especially 1:1 to 50:1, particularly 1:2 to 30:1. Moreparticularly, where an alumoxane cocatalyst is used, then for anunsupported catalyst the aluminium:metallocene metal (M) molar ratio isconveniently 2:1 to 10000:1, preferably 50:1 to 1000:1. Where thecatalyst is supported the Al:M molar ratio is conveniently 2:1 to10000:1 preferably 50:1 to 400:1. Where a borane cocatalyst (catalystactivator) is used, the B:M molar ratio is conveniently 2:1 to 1:2,preferably 9:10 to 10:9, especially 1:1. When a neutral triarylborontype cocatalyst is used the B:M molar ratio is typically 1:2 to 500:1,however some aluminium alkyl would normally also be used. When usingionic tetraaryl borate compounds, it is preferred to use carboniumrather than ammonium counterions or to use B:M molar ratio 1:1.

[0148] Where the further material is loaded onto the catalyst loadedsupport material, the support may be recovered and if desired driedbefore use in olefin polymerization.

[0149] The olefin polymerized in the method of the invention ispreferably ethylene or an alpha-olefin or a mixture of ethylene and anα-olefin or a mixture of alpha olefins, for example C₂₋₂₀ olefins, e.g.ethylene, propene, n-but-1-ene, n-hex-1-ene, 4-methyl-pent-1-ene,n-oct-1-ene etc. The olefins polymerized in the method of the inventionmay include any compound which includes unsaturated polymerizablegroups. Thus for example unsaturated compounds, such as C₆₋₂₀ olefins(including cyclic and polycyclic olefins (e.g. norbornene)), andpolyenes, especially C₆₋₂₀ dienes, may be included in a comonomermixture with lower olefins, e.g. C₂₋₅ α-olefins. Diolefins (i.e. dienes)are suitably used for introducing long chain branching into theresultant polymer. Examples of such dienes include α, ω linear dienessuch as 1,5-hexadiene, 1,6-heptadiene, 1,8-nonadiene, 1,9-decadiene,etc.

[0150] In general, where the polymer being produced is a homopolymer itwill preferably be polyethylene or polypropylene. Where the polymerbeing produced is a copolymer it will likewise preferably be an ethyleneor propylene copolymer with ethylene or propylene making up the majorproportion (by number and more preferably by weight) of the monomerresidues. Comonomers, such as C₄₋₆ alkenes, will generally beincorporated to contribute to the mechanical strength of the polymerproduct.

[0151] Usually metallocene catalysts yield relatively narrow molecularweight distribution polymers; however, if desired, the nature of themonomer/monomer mixture and the polymerization conditions may be changedduring the polymerization process so as to produce a broad bimodal ormultimodal molecular weight distribution (MWD) in the final polymerproduct. In such a broad MWD product, the higher molecular weightcomponent contributes to the strength of the end product while the lowermolecular weight component contributes to the processability of theproduct, e.g. enabling the product to be used in extrusion and blowmoulding processes, for example for the preparation of tubes, pipes,containers, etc.

[0152] A multimodal MWD can be produced using a catalyst material withtwo or more different types of active polymerization sites, e.g. withone such site provided by the metallocene on the support and furthersites being provided by further catalysts, e.g. Ziegler catalysts, othermetallocenes, etc. included in the catalyst material.

[0153] Polymerization in the method of the invention may be effected inone or more, e.g. 1, 2 or 3, polymerization reactors, using conventionalpolymerization techniques, e.g. gas phase, solution phase, slurry orbulk polymerization.

[0154] In general, a combination of slurry (or bulk) and at least onegas phase reactor is often preferred, particularly with the reactororder being slurry (or bulk) then one or more gas phase.

[0155] For slurry reactors, the reaction temperature will generally bein the range 40 to 110° C. (e.g. 85-110° C.), the reactor pressure willgenerally be in the range 5 to 80 bar (e.g. 50-65 bar), and theresidence time will generally be in the range 0.3 to 5 hours (e.g. 0.5to 2 hours). The diluent used will generally be an aliphatic hydrocarbonhaving a boiling point in the range −70 to +100° C. In such reactors,polymerization may if desired be effected under supercriticalconditions.

[0156] For gas phase reactors, the reaction temperature used willgenerally be in the range 60 to 115° C. (e.g. 70 to 110° C.), thereactor pressure will generally be in the range 10 to 25 bar, and theresidence time will generally be 1 to 8 hours. The gas used willcommonly be a non-reactive gas such as nitrogen together with monomer(e.g. ethylene).

[0157] For solution phase reactors, the reaction temperature used willgenerally be in the range 130 to 270° C., the reactor pressure willgenerally be in the range 20 to 400 bar and the residence time willgenerally be in the range 0.005 to 1 hour. The solvent used willcommonly be a hydrocarbon with a boiling point in the range 80-200° C.

[0158] Generally the quantity of catalyst used will depend upon thenature of the catalyst, the reactor types and conditions and theproperties desired for the polymer product. Conventional catalystquantities, such as described in the publications referred to herein,may be used.

[0159] The invention will now be illustrated by reference to thefollowing non-limiting Examples:

Ligand and Complex Synthesis

[0160] All operations are carried out under an argon or nitrogenatmosphere using standard Schlenk, vacuum and drybox techniques. Ether,tetrahydrofuran (THF) and toluene solvents were dried with potassiumbenzophenone ketyl and distilled under argon prior to use. Othersolvents were dried using 13X+13 Å molecular sieves. All other chemicalswere used as commercially available.

[0161] NMR spectra were recorded using a JEOL JNM-EX270 MHz FT-NMRspectrometer with tetramethylsilane (TMS) as an internal reference.

[0162] Direct inlet mass spectra were recorded using a VG TRIO 2quadruple mass spectrometer in electron impact ionization mode (70 eV).

[0163] GC-MS analysis was performed using a Hewlett Packard 6890/5973Mass Selective Detector in electron impact ionization mode (70 eV),equipped with a silica capillary column (30 m×0.25 mm i.d).

EXPERIMENTAL; Complex Synthesis

[0164] General Considerations. All reactions with organometallicreagents were carried out in an argon atmosphere using standard Schlenktechniques. Solvents were dried and distilled under argon prior to use.Merck Silica 60 (0.1% Ca) was employed in chromatographic purifications.

[0165] Preparation ofrac-[ethylenebis(4-(tert-butyldimethylsiloxy)-indenyl]-zirconiumdichloride (5)

[0166] 4-(tert-Butyldimethylsiloxy)-1-indanone (1). To a solution of4-hydroxy-1-indanone (25.0 g, 169 mmol) and imidazole (28.7 g, 422 mmol)in DMF (500 ml) was added tert-butyldimethylchiorosilane. The reactionmixture was stirred overnight at room temperature and treated with water(500 ml) and extracted with diethyl ether (500 ml). The organic phasewas collected and dried over sodium sulfate. Evaporation gave a yellowoil which was distilled under reduced pressure to give indanone (1)(35.44 g, 135 mmol, 79.9%) as a colourless oil (120-121° C./0.1 mbar).

[0167] 4-(tert-Butyldimethylsiloxy-1-indanone tosylhydrozone (2). To asolution of indanone (1) (30.0 g, 114 mmol) in methanol (1000 ml) wasadded p-toluenesulfonyl-hydrazide (21.29 g, (114 mmol) and 10 drops ofconcentrated sulfuric acid. The reaction mixture was then heated underreflux for 3 hours, whereafter the solution was concentrated and acrystallization followed overnight at room temperature. The crystallinetosylhydrozone (2) (40.38 g, 93.8 mmol, 82.2%) was isolated byfiltration.

[0168] 4-(tert-Butyldimethylsiloxy)-indene (3). To a solution oftosylhydrozone (2) (34.87 g, 81 mmol) in THF (350 ml) at 0° C. was addeddropwise n-butyllithium (99 ml, 247 mmol, 2.5 M solution in hexane).After the addition was complete the solution was stirred at roomtemperature overnight. The reaction solution was then treated with icewater (400 ml) and acidified with hydrochloric acid (5% solution). Theacidic solution was extracted with diethyl ether (3×250 ml), the organicfractions were combined and washed successively with aqueous sodiumbicarbonate solution and brine, and dried over sodium sulfate. Thesolvents were removed by evaporation and the remaining yellow oil wasdistilled under reduced pressure to give indene (3) (6.94 g, 28.2 mmol,34.8%) as a pale yellow oil (82-83° C./0.2 mbar) as a mixture of twodoublebond (1H and 3H) isomers.

[0169] Bis(4-(tert-butyldimethylsiloxy)-1-indenyl) ethane (4). To an icecooled solution of indene (3) (8.5 g, 34.5 mmol) in THF (50 mL) wasadded n-BuLi (15.2 ml, 37.9 mmol, 2.5 M solution in hexane) and thereaction mixture stirred for two hours at room temperature. The solutionwas then cooled to −80° C. and a solution of dibromoethane (3.24 g. 17.3mmol) in THF. (15 ml) was added dropwise. After addition was complete,the temperature of the reaction solution was slowly allowed to rise toroom temperature and stirred overnight. The resulting solution waswashed with saturated ammonium chloride solution (100 ml) and extractedwith diethyl ether (2×100 ml). The organic fractions were combined anddried over sodium sulfate. Solvents were evaporated and the remainingoil was dissolved in a methanol/acetone mixture (3:1), cooling to −30°C. gave (4) (0.68 g, 7.6) as a yellowish crystalline solid.

[0170] Rac-[ethylenebis (4-(tert-butyldimethylsiloxy)-indenyl]-zirconiumdichloride (5). To a solution of (4) (0.68 g, 1.3 mmol) in THF (25 mL)at 0° C. was added dropwise n-BuLi (1.05 ml, 2.63 mmol, 2.5 M solutionin hexane), and the reaction mixture was stirred for three hours at roomtemperature. The resulting solution was added dropwise to a suspensionof ZrCl₄ (0.39 g, 1.7 mmol) in THF (25 mL) at −80° C. The reactionmixture was gradually warmed to room temperature and stirred overnight.The solvents were evaporated, the remaining solid was extracted withCH₂Cl₂ (100 ml) and filtrated through Celite to remove lithium chloride.The solvent was evaporated and the crude product was extracted withdiethyl ether (200 ml) and filtrated through Celite. Concentration andcooling to −30° C. gave (5) (50 mg, 5.6%) as yellow microcrystals.

[0171] This reaction sequence is depicted in Diagram 1 below.

[0172] Preparation ofrac-[dimethylsilylenebis(4-(tert-butyldimethylsiloxy)-2-methyl-indenyl)]-zirconiumdichloride (10)

[0173] 7-hydroxy-2-methyl-1-indanone (6) was prepared according to theprocedure described by Bringmann and Jansen (Liebigs Ann. Chem. 1985,2116-2125).

[0174] 7-(tert-butyldimethylsiloxy)-2-methyl-1-indanone (7). To asolution of 7-hydroxy-2-methyl-1-indanone (6) (10.2 g, 37 mmol) andimidazole (3.02 g, 44 mmol) dissolved in DMF (200 ml) was addedtert-butyldimethylchlorosilane (6.11 g, 41 mmol) in DMF (50 ml). Thereaction mixture was stirred overnight at room temperature and treatedwith water (200 ml) and extracted with diethylether (2×200 ml). Thecombined organic phases were washed with aqueos NH₄Cl (300 ml), brine(100 ml) and dried over sodium sulfate. Evaporation gave (7) as a yellowoil which was used without further purification.

[0175] 7-(tert-butyldimethylsiloxy)-2-methyl-1-indene (8). To a solutionof 7 (13.0 g, 47.1 mmol) in THF/methanol (2:1, 500 ml) was added sodiumborohydride (3.67 g, 94 mmol) in several portions. The reaction mixturewas stirred at room temperature overnight. The clear colorless solutionwas diluted with diethylether (300 ml), washed with 5% HCl (2×300 ml),saturated aqueous NaHCO₃ (300 ml), brine (200 ml) and dried overanhydrous Na₂SO₄. Evaporation of volatiles gave brownish oil which wasused without further purification.

[0176] The oil (11.2 g) was dissolved in toluene (300 ml) and anhydrousoxalic acid (10.8 g, 120 mmol) was added. The mixture was heated at 100°C. for 1 hour and allowed to cool to room temperature. After decantingthe solution on water it was diluted with diethyl ether (400 ml). Theorganic phase was washed with water (300 ml), 5% HCl (2×300 ml),saturated aqueous NaHCO₃ (300 ml), brine (200 ml) and dried overanhydrous Na₂SO₄. The solvents were removed under reduced pressure togive brown oil. The crude product was purified by flash chromatography(99% hexane/1% ethyl acetate) to yield 8 (3.1 g) as a colorless oil.

[0177]Bis(4-(tert-butyldimethylsiloxy)-2-methyl-1-indenyl)dimethylsilane (9).To an ice cooled solution of 8 (2.70 g, 10.4 mmol) in THF (50 mL) wasadded n-BuLi (4.2 ml, 10.5 mmol, 2.5 M solution in hexane) dropwise. Theice bath was removed 5 minutes after completion of the addition ofn-BuLi and the reaction mixture was stirred for 40 minutes at roomtemperature. The orange solution was then cooled to 0° C. and a solutionof dichlorodimethylsilane (0.67 g, 5.2 mmol) in THF (5 ml) was dropwiseadded. The reaction mixture was slowly allowed to attain roomtemperature and stirred overnight. The resulting solution was washedwith saturated ammonium chloride solution (100 ml) and extracted withdiethyl ether (2×100 ml). The organic fractions were combined and driedover sodium sulfate. The solvents were evaporated and the remaining oilwas purified by flash chromatography (99% pentane/1% diethyl ether) toyield a mixture of rac- and meso-9 (1.91 g, 64%) as a yellow oil.

[0178]Rac-[dimethylsilylenebis(4-(tert-butyldimethylsiloxy)-2-methyl-indenyl)]-zirconiumdichloride (10). To a pale yellow solution of 9 (0.42 g, 0.73 mmol) inEt₂O (15 mL) at −40° C. was added dropwise n-BuLi (0.60 ml, 1.50 mmol,2.5 M solution in hexane) and the reaction mixture was stirred for 15minutes at −40° C. and then at room temperature for 1.5 hours. Thesolvent was removed in vacuo and the resulting yellowish powder wasmixed with ZrCl₄ (0.17 g, 0.73 mmol). Precooled CH₂Cl₂ (−80° C., 50 ml)was added at −80° C. The resulting red suspension was gradually warmedto room temperature and stirred overnight. The resulting red solutionwas filtered through Celite to remove lithium chloride and the solventwas evaporated. The crude product was extracted with Et₂O, concentratedand cooled to −30° C. to give 10 as an orange powder.

[0179] This reaction sequence is depicted in Diagram 2 below.

[0180] Preparation of[(N-tert-butyl-amido)-dimethyl-(η⁵-inden-4-yloxy)-silane)]-titaniumdichloride (15)

[0181] 4-(tert-Butyldimethylsiloxy)-1-indanone (1). To a solution of4-hydroxy-1-indanone (25.0 g, 169 mmol) in DMF (500 ml) wastriethylamine (22.2 g, 220 mmol) added, to the resulting solution wastert-butyldimethylchlorosilane (28.0 g, 186 mmol) added. The reactionmixture was stirred overnight at room temperature and treated with water(500 ml) and extracted with diethyl ether (500 ml). The organic phasewas collected and dried over sodium sulfate. Evaporation gave a yellowoil which was distilled under reduced pressure to give the indanone(36.68 g, 140 mmol, 82.7%) as a colourless oil (120-121° C./0.1 mbar).

[0182] 4-Hydroxyindene (11). To a solution of4-(tert-butyldimethylsiloxy)-1-indanone (35.0 g, 133 mmol) inmethanol/THF (100 ml:200 ml) was NaBH₄ (7.57 g, 200 mmol) added inportions at 0° C. The reaction mixture is stirred overnight. Theresulting solution is poured on ice, acidified with concentratedhydrochloric acid to pH=1 and extracted with diethyl eter (2×200 ml).The organic fractions were combined and washed with brine, water anddried over sodiumsulfate. The solvents were evaporated and the remainingoil (siloxyindanol) was dissolved in toluene (300 ml). To this solutionwas oxalic acid (24.0 g, 267 mmol) added. The mixture was heated underreflux for 3 hours, whereafter the reaction mixture was washed with a10% aqueous solution of NaHCO₃ and dried over sodiumsulfate. The solventwas removed by evaporation. The remaining yellow oil was dissolved inTHF (300 ml) and treated with tetra-n-butylammonium fluoride (69.6 g,266 mmol) at 0° C. and stirred for 30 min at room temperature. Thereaction solution was treated with a saturated NH₄Cl solution (200 ml)and extracted with diethyl ether (2×200 ml) The organic phase wascollected, evaporation of solvent left a solid which was recrystallizedfrom methanol to give a pale yellow solid (11.45 g, 86.6 mmol, 65.10%).

[0183] N-(tert-Butyl)-N-(1-(1H-4-indenyloxy)-1,1-dimethylsilyl)amine(12). 4-Hydroxyindene (9.25 g, 70 mmol) was dissolved inmethylenechloride (200 ml) and the solution was cooled to 0° C. To thissolution was triethylamine (10.7 g, 105 mmol) added. The reactionmixture was stirred for 1 h and thenN-(tert-butyl)-N-(1-chloro-1,1-dimethylsilyl)amine (13.95 g, 84 mmol)added. The mixture was stirred for 2 h at 0° C. and then the flask waswarmed to room temperature and stirred overnight. The solvent was thenremoved by evaporation and the residue was extracted with hexane (2×40ml) and filtered. Solvent was removed under reduced pressure leaving14.6 g (56 mmol, 79.8%) of the silylamine as a yellow liquid.

[0184] N-(tert-Butyl)-N-(1-(1H-4-indenyloxy)-1,1-dimethylsilyl)aminedilithium salt (13). To a solution ofN-(tert-Butyl)-N-(1-(1H-4-indenyloxy)-1,1-dimethylsilyl)amine (13.6 g,52 mmol) in hexane (200 ml) at 0° C. was added dropwise t-butyllithium(86 ml, 129 mmol, 1.5 M solution in pentane). The reaction mixture wasstirred overnight at room temperature. The resulting off-whiteprecipitate was collected via filtration, washed with hexane (100 ml)and dried under reduced pressure to give 9.8 g (36 mmol, 69.2%) of thedilithium salt as an off-white solid.

[0185] [(N-tert-butylamido)-dimethyl-(η⁵-inden-4-yloxy)-silane]-titaniumdichloride (14). TiCl₃(THF)₃ (7.1 g, 19.1 mmol) was suspended in THF (50ml). To this solution was a solution ofN-(tert-butyl)-N-(1-(1H-4-indenyloxy)-1,1-dimethylsilyl)amine dilithiumsalt (5.2 g, 19.1 mmol) in THF (200 ml) added. The reaction solution wasstirred for 1 h. To the resulting solution was PbCl₂ (3.45 g, 12.4 mmol)added and the solution was stirred for 1 h. The solvent was removedunder reduced pressure. The residue was then extracted with toluene (50ml), the solution was filtered, and the toluene was removed underreduced pressure. The residue was then titrated with hexane (50 ml) andthe precipitate was collected via filtration, washed with hexane anddried under vacuum to give the titanium dichloride (3.72 g, 9.9 mmol,51.6%) as an orange solid.

[0186] This reaction sequence is depicted in Diagram 3 below.

Polymerization Reactions

[0187] Ethylene (>99.95%), nitrogen (>99.999%) and n-pentane (>97%) wereused. 1-Hexene was purified by refluxing over sodium and distillationunder an atmosphere of nitrogen.

[0188] Catalysts were prepared by mixing the co-catalyst (30 wt % MAO intoluene or 70 wt % HIBAO in toluene, both from Albemarle) in toluene toreach the desired Aluminium: M (Metal) molar ratio.

[0189] A feeding vessel in a glove box was charged with an appropriateamount of catalyst and transferred to a stirred (400 min⁻¹) Büchi2.0/3.0 L stirred autoclave reactor. The reactor was purged withnitrogen and charged with n-pentane at ambient temperature. The reactortemperature was adjusted to +80° C. and the feed of ethylene into thereactor begun. The partial pressure of ethylene (10⁶ Pa (10.0 bar)) andtotal pressure (1.3×10⁶ Pa (13 bar)) were held constant by continuouslyfeeding in monomer. After 30 minutes the reactor was vented and thepolymer isolated.

[0190] When 1-hexene was used as comonomer its addition to the reactorwas simultaneous with ethylene.

[0191] Table 1 below provides details of the polymerisations conducted.The catalysts used were either compound (5) (infra) orrac-[ethylenebis(2-(tertbutyldimethylsiloxy)-indenyl)]zirconiumdichloride which is disclosed in WO97/28170 (infra). TABLE 1 HDPE LLDPEHDPE Compound LLDPE Compound HDPE HDPE Polymer type Comparative (5) ofComparative (5) of Comparative Compound (5) Complex example exampleexample example example of example Catalyst amount 0.25 μmol 0.52 μmol0.27 μmol 0.5 μmol 0.25 μmol 1.27 μmol Polymer amount 108 130 165 225 5247 (g) Polymerisation 30 60 30 30 30 60 time (Min) Cocatalyst MAO MAOMAO MAO HIBAO HIBAO Aluminium/ 1000 900 900 900 1000 916 Metal ratioActivity of metal 9472 2766 13399 9855 4560 433 (KgPol/g met h)Comonomer — — 1-hexene 1-hexene — — Comonomer — — 50.0 30.0 — — amount(ml) Comonomer — — 2.4 3.3 — — amount (w-%) Medium PENTANE ISOBUTANEPENTANE ISOBUTANE PENTANE ISOBUTANE Medium amount 1200 1800 1200 18001200 1800 (ml) Pressure tot (bar) 14 23 13 23 14 23 Temperature (° C.)80 80 80 95 80 80 CRYSTALLINITY (%) 67 64 53 43 71 — MELTING TEMP (° C.)135 134 122 116 133 — MFR₂ (g/10 min) n.a. <0.1 1.4 n.a. 132 — MFR₂₁(g/10 min) 7.5 120 46.20 0.10 47.50 — BD (kg/m3) 70.00 — 178 — 190 —T-VINYLENE (C = C/1000C) 0.01 0.04 0.00 0.04 0.01 — VINYL (C—C/1000C)0.50 0.34 0.53 0.17 0.62 — VINYLIDENE (C—C/1000C) 0.02 0.04 0.03 0.060.01 — M_(n) 44300 63600 35200 143000 35700 — M_(w) 145000 270000 86600477000 88700 — MWD 3.3 4.2 2.5 3.3 2.5 —

1. A metallocene catalyst in which the metal is coordinated by a η⁵ cyclopentadienyl ligand which forms part of an indenyl or indenyloid moiety, characterised in that said moiety is directly or indirectly substituted at the 4- 5-, 6- or 7-position by a pendant siloxy or germyloxy group.
 2. A catalyst as claimed in claim 1 of formula (III) (Lig)_(p) M(X)m(A)_(n)   (III) in which: M is a transition metal ion or a lanthanide metal ion; p is 1 or 2; m is greater than or equal to 0; n is greater than or equal to 0; n+m is equal to the valency of the metal not satisfied by ligand or ligands Lig; X is a ligand which co-ordinates to M selected from a η⁵ hydrocarbyl, η¹ hydrocarbyl, halo, hydrocarbyl amino or hydrocarbyl amido ligand; A is a σ-ligand; and each ligand Lig which may be the same or different is a η⁵ cyclopentadienyl ligand which forms part of an indenyl or indenyloid moiety, characterised in that said moiety is directly or indirectly substituted at the 4- 5-, 6- or 7-position by a pendant siloxy or germyloxy group
 3. A catalyst as claimed in claim 1 or 2 wherein M is a group 4 to 6 transition metal.
 4. A catalyst as claimed in claim 3 wherein said metal is Cr, Ti, Zr or Hf.
 5. A catalyst as claimed in anyone of claims 2 to 4 wherein p is 2 and m is zero.
 6. A catalyst as claimed in any one of claims 2 to 5 wherein each A is a halo, amido or C₁₋₁₂-hydrocarbyl ligand.
 7. A catalyst as claimed in claim 6 wherein each A is a chloro ligand.
 8. A catalyst as claimed in any one of claims 2 to 7 wherein each Lig is independently a negatively charged indenyl or indenyloid moiety of the following formula (IV):

wherein one or more of the ring carbon atoms may be replaced by a ring heteroatom; each Q is either a silicon or a germanium atom; either or both of the bonds shown as—may be present or absent; each R¹ which may be the same or different is a hydrogen or a C₁₋₂₀ hydrocarbyl or a η¹ ligand, at least one R¹ being other than hydrogen; each R² is a hydrogen or a group bonded to the 5-membered ring through a carbon, oxygen, silicon, phosphorus, germanium, nitrogen or sulfur atom; each R³ is a hydrogen or a group bonded to the 6-membered ring through an atom of groups 14, 15 or 16 of the periodic table (IUPAC) carbon, oxygen, silicon, germanium, nitrogen, phosphorus or sulfur atom; or two or more R² and/or two or more R³ groups attached to adjacent ring atoms on the same ring together form a 5- to 8-membered fused ring; and optionally one R² or R³ is -L-Z wherein L is a 1 to 4 atom chain and Z is a second moiety of formula (IV) and joined to L through one R² or R³, if present in which L is one and the same chain common to both moieties, a is an integer between 1 and 3, b is an integer between 1 and 3, the sum of a and b being no more than 4, c is an integer between 1 and 3, with the proviso that no more than one -L-Z group is present in each ligand.
 9. A catalyst as claimed in claim 8 wherein all the ring atoms are carbon atoms.
 10. A catalyst as claimed in claim 8 or 9 wherein both—bonds are present.
 11. A catalyst as claimed in any one of claim 8 to 10 wherein Q is Si.
 12. A catalyst as claimed in any one of claims 8 to 11 wherein each R¹ is independently a C₁₋₈ hydrocarbyl or C₁₋₈ alkylamine.
 13. A catalyst as claimed in any one of claims 8 to 12 wherein R³ is a group bonded to the 6-membered ring through a carbon, oxygen, silicon, germanium, nitrogen, phosphorus or sulfur atom.
 14. A catalyst as claimed in any one of claim 8 to 13 wherein each R or R is independently a C₁₋₂₀ hydrocarbyl, C₁₋₂₀ hydrocarbyl siloxy, C₁₋₂₀ hydrocarbyloxy, C₁₋₂₀ hydrocarbyl silyl group.
 15. A catalyst as claimed in claim 14 wherein each R² or R³ is independently a C₁₋₈ hydrocarbyl group or C₁₋₂₀ hydrocarbylsiloxy group attached to the ring via the oxygen atom.
 16. A catalyst as claimed in any one of claims 8 to 12 wherein R³ is H.
 17. A catalyst as claimed in any one of claims 8 to 16 wherein a group L-Z is present at the 1 or 3 position of formula (IV).
 18. A catalyst as claimed in claim 17 wherein L is SiR² ₂ or (CR² ₂)_(q) in which q is 1 to 3 and R₂ is as hereinbefore defined.
 19. A catalyst as claimed in claim 18 wherein L is (CH₂)_(q) or Si(CH₃)₂.
 20. A catalyst as claimed in any of claims 8 to 19 wherein at least one group —OQ(R¹)₃ is a siloxy or germyloxy group directly attached to the 4-position or 7-position.
 21. A catalyst as claimed in any one of claims 8 to 20 where a, b and c are
 1. 22. A catalyst as claimed in any one of claims 8 to 20 wherein at least two groups —OQ(R¹)₃ are present, one at position 4, one at position 7 of formula (IV).
 23. A catalyst as claimed in any one of claims 8 to 22 wherein (R¹)₃QO— is selected from the group consisting of OSi(CH₃)₂N(C₁₋₆-alkyl)H,


24. A catalyst as claimed in any one of claims 8 to 23 wherein Z is present and both moieties of formula (IV) are identical.
 25. A catalyst as claimed in claim 2 wherein Lig is of formula

wherein R¹, R², R³, Q and L are as hereinbefore defined.
 26. An olefin polymerisation catalyst system comprising or produced by the reaction of: (i) a metallocene catalyst as claimed in any one of claims 1 to 25; and (ii) a cocatalyst/catalyst activator.
 27. A process for olefin polymerisation comprising polymerising an olefin in the presence of a metallocene catalyst as claimed in claim 1 to
 25. 28. A process for the preparation of a metallocene catalyst as claimed in any one of claim 1 to 25 which comprises metallating a η⁵ cyclopentadienyl ligand which forms part of an indenyl or indenyloid moiety with a transition metal or a lanthanide, characterised in that said moiety is directly or indirectly substituted at the 4- 5-, 6- or 7-position by a pendant siloxy or germyloxy group.
 29. A compound of formula (IV)

(wherein one or more of the ring carbon atoms may be replaced by a ring heteroatom; each Q is either a silicon or a germanium atom; either or both of the bonds shown as—may be present or absent; each R¹ which may be the same or different is a hydrogen or a C₁₋₂₀ hydrocarbyl or a η¹ ligand example a σ ligand at least one R¹ being other than hydrogen at least one group (R¹)₃QO— being present on the 4 or 7 position; each R² may be hydrogen or a group bonded to the 5-membered ring through an atom of groups 14, 15 ot 16 of the periodic table (IUPAC) carbon, oxygen, silicon, germanium, nitrogen or sulfur; each R³ may be hydrogen or a group bonded to the 6-membered ring through an atom of groups 14, 15 ot 16 of the periodic table (IUPAC); or two or more R² and/or two or more R³ groups attached to adjacent ring atoms on the same ring together form a 5- to 8-membered fused ring; and optionally one R² or R³ is -L-Z wherein L is a 1 to 4 atom chain and Z is a second moiety of formula (IV) and joined to L through one R² or R³, if present in which L is one and the same chain common to both moieties, a is an integer between 1 and 3, b is an integer between 1 and 3, the sum of a and b being no more than 4, c is an integer between 1 and 3, with the proviso that no more than one -L-Z group is present in each ligand In) and salts and complexes thereof. 